The Washington Post has become the second newspaper in the country to publish monthly and yearly indexes and abstract of its contents.

The first copy of "The Official Washington Post Index" was published last week under an agreement with Newpaper Archive Developments Ltd., a subsidiary of the Times Newpaper of London and Research Publications Inc. of Woodbridge, Conn., which already produces the Times of London, the Post on microfilm last January and to increase those sales began publishing the index, according to Research Publications President Milton Mandel.

"What we're doing is competing with the New York Times index," Mandel said. The index will "recognize the Post as a newspaper of record."

Mandel said subscriptions, which are $200 a year for the introductory price and about $285 after that, will be aimed toward libraries colleges and businesses. About 500 such institutions already purchase Post microfilm, Mandel said.

The first edition to be published so far contains new stories that appeared in the paper during January 1979. Excluded are articles "clearly lacking in permanent historical value" such as television schedules, classified ads, and columns about gossip, health, stamps and coins, the index said.

Included are news and feature articles, editorials, syndicated columns, reviews, sports, obituaries, cartoons, photographs and advertising containing information of permanent value the index said.

Stories are listed alphabetically, usually by subject, and contain a one or two sentence description of the article's contents. Also listed is the date of publication, the page on which it appeared and the column.